Recent studies indicate that losses in sensitivity to temporal luminance changes are often the earliest symptom of retinitis pigmentosa (RP) and other pathological conditions including multiple sclerosis (MS), glaucoma, optic neuritis, and certain drug toxicities. The goal of the present project is to discover those psychophysical measures of temporal sensitivity which constitute the most effective early diagnostic tests. During the current support period, we have developed a battery of potentially useful test routines, designed to be administered by an automated portable test device. This device uses an inexpensive microcomputer to control stimulus generation, response collection, data analysis, and display of results. Preliminary measurements with the device readily demonstrate deficits in temporal sensitivity in known RP patients. Continued support is requested to administer the current battery to a large population of volunteer subjects, including those with diagnosed pathological conditions other than RP. In Rochester subjects will be recruited from among patients seen at the University of Rochester's Department of Ophthalmology, including suspected RP cases from students enrolled at the National Technical Institute for the Deaf. Additional patient referrals and age-matched control subjects will be obtained from among persons seen at the Medical Eye Service Facility at Kodak Park. In Boston subjects will be recruited from patients seen at the Clinical Research Facility of the Eye Research Foundation. Special efforts will be made to obtain repeated measures from patients under continuing treatment, and to test known or suspected carriers for RP. By obtaining subjects from these sources, extensive independent diagnostic information will be available, making it possible to correlate the proposed psychophysical test results with other clinical measures, and thereby to evaluate their sensitivity and specificity in detecting known pathological conditions. A further goal of the proposed project is to develop several new potentially useful psychophysical tests, including static dark-adapted perimetry, incremental flicker fusion and luminance masking. We hope to discover sensitive, objective and non-invasive means for early identification of RP and other pathological conditions, thereby improving the opportunity for successful treatment.